U.S. patent application number 10/423314 was filed with the patent office on 2003-10-30 for ultra-accelerated natural sunlight exposure testing facilities.
Invention is credited to Jorgensen, Gary J., Lewandowski, Allan A..
Application Number | 20030200824 10/423314 |
Document ID | / |
Family ID | 24077903 |
Filed Date | 2003-10-30 |
United States Patent
Application |
20030200824 |
Kind Code |
A1 |
Lewandowski, Allan A. ; et
al. |
October 30, 2003 |
Ultra-accelerated natural sunlight exposure testing facilities
Abstract
A multi-faceted concentrator apparatus for providing
ultra-accelerated natural sunlight exposure testing for sample
materials under controlled weathering conditions comprising: facets
that receive incident natural sunlight, transmits VIS/NIR and
reflects UV/VIS onto a secondary reflector that delivers a uniform
flux of UV/VIS onto a sample exposure plane located near a center
of a facet array in chamber means that provide concurrent levels of
temperature and/or relative humidity at high levels of up to
100.times. of natural sunlight that allow sample materials to be
subjected to accelerated irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a years worth representative
weathering of sample materials.
Inventors: |
Lewandowski, Allan A.;
(Evergreen, CO) ; Jorgensen, Gary J.; (Pine,
CO) |
Correspondence
Address: |
PAUL J WHITE, SENIOR COUNSEL
NATIONAL RENEWABLE ENERGY LABORATORY (NREL)
1617 COLE BOULEVARD
GOLDEN
CO
80401-3393
US
|
Family ID: |
24077903 |
Appl. No.: |
10/423314 |
Filed: |
April 25, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10423314 |
Apr 25, 2003 |
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09521731 |
Mar 9, 2000 |
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6604436 |
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09521731 |
Mar 9, 2000 |
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09006746 |
Jan 13, 1998 |
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6073500 |
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Current U.S.
Class: |
73/865.6 |
Current CPC
Class: |
G01N 17/004
20130101 |
Class at
Publication: |
73/865.6 |
International
Class: |
G01N 017/00 |
Goverment Interests
[0002] The United States Government has rights in this invention
pursuant to Contract No. DE-AC36-83CH10093 between the United
States Department of Energy and the Midwest Research Institute.
Claims
We claim:
1. A multi-faceted concentrator apparatus for providing
ultra-accelerated natural sunlight exposure testing for sample
materials under controlled weathering conditions comprise: means
for concentrating solar flux uniformly as concentrated uniform
reflected light; means for directing said concentrated uniform
reflected light, and means for directing said concentrated uniform
reflected light onto sample materials contained in a chamber having
means to provide single or multiple concurrent levels of
temperature and/or relative humidity, wherein said means for
concentrating solar flux uniformly and means for directing
concentrated uniform reflected light comprise: a multi-faceted
concentrator comprising facets that receive incident natural
sunlight, transmits VIS/NIR and reflects a uniform flux of UV/VIS
onto a sample exposure plane located at or near aim points of said
facets in chamber means that provide concur-rent levels of
temperature and/or relative humidity that allow sample materials to
be subjected to accelerated irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a years worth of
representative weathering of sample materials.
2. The apparatus of claim 1 wherein said multi-faceted concentrator
comprises: facets that receive incident natural sunlight, transmits
VIS/NIR and reflects UV/VIS onto a secondary reflector that
delivers a uniform flux of UV/VIS onto a sample exposure plane
located near a center of a facet array in chamber means that
provide concurrent levels of temperature and/or relative humidity
that allow sample materials to be subjected to accelerated
irradiance exposure factors for a significant period of time of
about 3 to 10 days to provide a corresponding time of about at
least a years worth representative weathering of sample
materials.
3. The apparatus of claim 1 wherein said multi-faceted concentrator
comprises: facets that receive incident natural sunlight, transmits
VIS/NIR and reflects a uniform flux of UV/VIS through a secondary
concentrator and onto a sample exposure plane located near an exit
of the secondary concentrator in chamber means that provide
concurrent levels of temperature and/or relative humidity that
allow sample materials to be subjected to accelerated irradiance
exposure factors for a significant period of about 3 to 10 days to
provide a corresponding time of about at least a years worth of
representative weathering of sample materials.
4. The apparatus of claim 1 wherein said multi-faceted concentrator
comprises: facets that receive incident natural sunlight, transmits
VIS/NIR and reflects UV/VIS onto a secondary concentrator which
delivers a uniform flux of UV/VIS onto a sample exposure plane
located below said secondary reflector to allow a horizontal
orientation of the sample chamber in which the sample exposure
plane is disposed.
5. The apparatus of claim 1 wherein said multi-faceted concentrator
comprises: a facet array that receives incident natural sunlight,
transmits VIS/NIR and reflects UV/VIS onto a secondary reflector
that reflects a uniform flux of UV/VIS onto a turning mirror
located near a center of the facet array; said turning mirror being
disposed to reflect said uniform flux of UV/VIS onto a sample
exposure plane located in a chamber below said turning mirror.
6. The apparatus of claim 1 wherein said multi-faceted concentrator
array comprises: facets that receive incident natural sunlight,
reflects a full spectrum of UV/VIS/NIR onto a secondary reflector
that transmits UV/NIR and reflects a uniform flux of UV/VIS onto a
sample exposure plane located in chamber means near said
multi-faceted concentrator array to provide concurrent levels of
temperature and/or relative humidity that allows sample materials
to be subjected to accelerated irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a years worth of
representative weathering of sample materials.
7. The apparatus of claim 1 wherein said multi-faceted concentrator
comprises: facets that receive incident natural sunlight, reflects
a full spectrum of UV/VIS/NIR onto a secondary reflector that
transmits VIS/NIR and reflects a uniform flux of UV/VIS onto a
sample exposure plane located in horizontally disposed chamber
means that provide concurrent levels of temperature and/or relative
humidity that allow sample materials to be subjected to accelerated
irradiance exposure factors for a significant period of time of
about 3 to 10 days to provide a corresponding time of about at
least a years worth of representative weathering of sample
materials.
8. The apparatus of claim 1 wherein said multi-faceted concentrator
comprises: facets that receive incident natural sunlight, reflects
a full spectrum of UV/VIS/NIR onto a secondary reflector that
transmits VIS/NIR and reflects a uniform flux of UV/VIS onto a
turning mirror that reflects said uniform flux of UV/VIS onto a
sample exposure plane located in horizontally disposed chamber
means that provide concurrent levels of temperature and/or relative
humidity that allow sample materials to be subject to accelerated
irradiance exposure factors for a significant period of time of
about 3 to 10 days to provide a corresponding time of about at
least a years worth of representative weathering of sample
materials.
9. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform reflected light, and means for directing
said concentrated uniform reflected light, and means for directing
said concentrated uniform reflected light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform reflected light comprising: i) a
multi-stepped concentrator that receives incident natural sunlight,
transmits VIS/NIR and reflects a uniform flux of UV/VIS onto a
vertically disposed sample exposure plane disposed in chamber means
about a common axis of reflective elements of said multi-stepped
concentrator to provide concurrent levels of temperature and/or
relative humidity that allow sample materials to be subjected to
accelerated irradiance exposure factors for a significant period of
time of about 3 to 10 days to provide a corresponding time of about
at least a years worth of representative weathering of sample
materials. ii) A multi-stepped concentrator that utilizes a
secondary reflector and/or turning mirror to reflect UV/VIS onto a
sample exposure plane located near the center or below the center
of the array.
10. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light comprising: i) a
front surface VIS/NIR reflective coating means to reflect VIS/NIR
and transmit UV/VIS. ii) a Fresnel lens means to receive
transmitted UV/VIS and transmit a desired spectral range of uniform
concentrated spectrally split natural sunlight; and iii) chamber
means capable of receiving said desired range of uniform
concentrated spectrally split natural sunlight in enclosed single
or multiple concurrent levels of temperature and/or relative
humidity providing means to allow sample materials to be subjected
to accelerated irradiance exposure factors for a significant period
of time of about 3 to 10 days to provide a corresponding time of
about at least a years worth of representative weathering of sample
materials.
11. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light comprising: i) a
Fresnel lens having a heat mirror coating on either its top or
bottom or both sides to reflect VIS/NIR and transmit UV/VIS; and
ii) chamber means capable of receiving transmitted UV/VIS in
enclosed single or multiple concurrent levels of temperature and/or
relative humidity providing means to allow sample materials to be
subjected to accelerated-irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a year's worth of
representative weathering of sample materials.
12. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprising: i) a Fresnel lens that receives incident
uniform, non-concentrated natural sunlight and transmits a desired
spectral range, a heat mirror means between said Fresnel lens and
sample materials that reflects VIS/NIR but transmits UV/VIS; and
ii) chamber means capable of receiving directed UV/VIS from said
heat mirror means that encloses multiple concurrent levels of
temperature and/or relative humidity providing means to allow
sample materials to be subjected to accelerated-irradiance exposure
factors for a significant period of time of about 3 to 10 days to
provide a corresponding time of about at least a years worth of
representative weathering of sample materials.
13. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform reflective light onto a sample
materials comprising: i) a Fresnel lens means that receive uniform
non-concentrated incident sunlight and transmits a desired spectral
range; ii) a cold relay mirror that receives said transmitted
desired spectral range and transmits VIS/NIR and reflects UV/VIS;
and iii) chamber means capable of receiving uniform accelerated
natural sunlight from said cold relay mirror to enclosed single or
multiple concurrent levels of temperature and/or relative humidity
providing means to allow sample materials to be subjected to
accelerated-irradiance exposure factors for a significant period of
time of about 3 to 10 days to provide a corresponding time of about
at least a years worth of representative weathering of sample
materials.
14. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprising: i) a first Fresnel/prism array that receives
incident uniform, non-concentrated natural sunlight and spatially
separates same into distinct wavelengths; ii) a second
Fresnel/prism array having a masking pattern on its top surface to
block unwanted wavelengths>.lambda..sub.cutoff of high VIS and
NIR and transmit and UV/VIS; and iii) chamber means capable of
receiving said recombined ultra-accelerated natural sunlight in
enclosed single or multiple concurrent levels of temperature and/or
relative humidity providing means to allow sample materials to be
subjected to accelerated-irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a years worth of
representative weathering of sample materials.
15. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprising: i) a first prism array to affect
spatially/distinct wavelengths from incident uniform,
non-concentrated sunlight and provide adjustable stop blocks of
accelerated .lambda.>.lambda..sub.UV/VIS or
.lambda.>.lambda..sub.c- utt-off; ii) a second prism array to
reconstruct or homogenize accelerated wavelengths from said first
prism array to provide a uniform distribution of spectrally
selected light; and iii) chamber means capable of receiving said
distribution of spectrally selected light in enclosed single or
multiple concurrent levels of temperature and/or relative humidity
providing means to allow sample materials to be subjected to
accelerated-irradiance exposure factors for a significant period of
time of about 3 to 10 days to provide a corresponding time of about
at least a years worth of representative weathering of sample
materials.
16. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a tracking primary Fresnel lens array that
receives incident uniform, non-concentrated natural sunlight; ii) a
secondary concentrator that transmits VIS/NIR wavelengths ranges
from said tracking primary lens array and reflects UV/VIS; and iii)
chamber means capable of receiving reflected UV/VIS in enclosed
single or multiple concurrent levels of temperature and/or relative
humidity providing means to allow sample materials to be subjected
to accelerated-irradiance exposure factors for a significant period
of time of about 3 to 10 days to provide a corresponding time of
about at least a years worth of representative weathering of sample
materials.
17. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a holographic means that receive uniform,
non-concentrated natural sunlight and spectrally splits said
sunlight into VIS/NIR and directs said UV/VIS into a chamber means;
and ii) chamber means capable of receiving UV/VIS in enclosed
single or multiple concurrent levels of temperature and/or relative
humidity providing means to allow sample materials to be subjected
to accelerated-irradiance exposure factors for a significant period
of time of about 3 to 10 days to provide a corresponding time of
about at least a years worth of representative weathering of sample
materials.
18. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a holographic device that receives and
concentrates incident uniformity, non-concentrated natural sunlight
and spectrally splits said sunlight into VIS/NIR and UV/VIS; and
ii) a secondary concentrator that receives said UV/VIS and directs
said UV/VIS into a chamber means; and iii) chamber means capable of
receiving said UV/VIS in enclosed single or multiple concurrent
levels of temperature and/or relative humidity providing means to
allow sample materials to be subjected to accelerated-irradiance
exposure factors for a significant period of time of about 3 to 10
days to provide a corresponding time of about at least a years
worth of representative weathering of sample materials.
19. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform reflective light onto a sample
materials comprises: i) a holographic means to receive incident
uniform, non-concentrated natural sunlight and transmit the same;
ii) a cold mirror that transmits VIS/NIR received from said
holographic means and reflects UV/VIS received from said
holographic means to a chamber means; and iii) chamber means
capable of receiving UV/VIS from said cold mirror into enclosed
single or multiple concurrent levels of temperature and/or relative
humidity providing means to allow sample materials to be subjected
to accelerated-irradiance exposure factors for a significant period
of time of about 3 to 10 days to provide a corresponding time of
about at least a years worth of representative weathering of sample
materials.
20. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a holographic device that receive incident
uniform, non-concentrated natural sunlight and spectrally splits
said sunlight into a VIS/NIR fraction and a UV/VIS fraction; ii) a
heat mirror that reflects the VIS/NIR fraction and transmits the
UV/VIS fraction onto a chamber means; and iii) chamber means
capable of receiving said UV/VIS fraction from the heat mirrors
into enclosed single or multiple concurrent levels of temperature
and/or relative humidity providing means to allow sample materials
to be subjected to accelerated-irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a years worth of
representative weathering of sample materials.
21. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a holographic device that receives incident
uniform, non-concentrated natural sunlight and spectrally splits
said sunlight into VIS/NIR and UV/VIS fractions; ii) a secondary
concentrator cold mirror that transmits VIS/NIR and reflects UV/VIS
onto chamber means; and iii) chamber means capable of receiving
reflected UV/VIS from said secondary concentrator cold mirror into
enclosed single or multiple concurrent levels of temperature and/or
relative humidity providing means to allow sample materials to be
subjected to accelerated-irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a years worth of
representative weathering of sample materials.
22. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a holographic device that receives incident
uniform, non-concentrated natural sunlight and spectrally splits
said sunlight into VIS/NIR and UV/VIS fractions; ii) a secondary
concentration that receives and concentrates said UV/VIS fraction;
and a heat mirror which reflects said VIS/NIR fraction; and iii)
chamber means capable of receiving said UV/VIS fraction from said
secondary concentrator into enclosed single or multiple concurrent
levels of temperature and/or relative humidity providing means to
allow sample materials to be subjected to accelerated-irradiance
exposure factors for a significant period of time of about 3 to 10
days to provide a corresponding time of about at least a years
worth of representative weathering of sample materials.
23. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a holographic device that receives incident
uniform, non-concentrated natural sunlight and reflects said
sunlight off of a secondary concentrator that is adjusted with the
primary tracking so as to reflect uniform, concentrated
ultra-accelerated natural sunlight on a horizontal fixed sample
plane; ii) chamber means capable of receiving said uniform
concentrated natural sunlight into enclosed single or multiple
concurrent levels of temperature and/or relative humidity providing
means to allow sample materials to be subjected to
accelerated-irradiance exposure factors for a significant period of
time of about 3 to 10 days to provide a corresponding time of about
at least a years worth of representative weathering of sample
materials.
24. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light, and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a 2-dimensional or 3-dimensional array
device of micro lenses that receive uniform, non-concentrated
natural sunlight and refractively concentrates and/or spectrally
splits said sunlight into VIS/NIR and UV/VIS fractions; and ii) a
surface means to transmit said VIS/NIR and reflect said UV/VIS; and
iii) chamber means capable of receiving refracted UV/VIS into
enclosed single or multiple concurrent levels of temperature and/or
relative humidity providing means to allow sample materials to be
subjected to accelerated-irradiance exposure factors for a
significant period of time of about 3 to 10 days to provide a
corresponding time of about at least a years worth of
representative weathering of sample materials
25. An apparatus for providing ultra-accelerated natural sunlight
exposure testing for sample materials under controlled weathering
conditions comprising: means for concentrating solar flux uniformly
as concentrated uniform refracted light and means for directing
said concentrated uniform refracted light onto sample materials
contained in a chamber having means to provide single or multiple
concurrent levels of temperature and/or relative humidity, wherein
said means for concentrating solar flux uniformly and means for
directing concentrated uniform refracted light onto a sample
materials comprises: i) a multi-faceted array of lenses device
means that receive incident uniform, non-concentrated natural
sunlight; ii) a heat mirror means that reflects a VIS/NIR fraction
of said sunlight and transmits a UV/VIS fraction of said sunlight;
and iii) chamber means capable of receiving said transmitted UV/VIS
fraction in enclosed single or multiple concurrent levels of
temperature and/or relative humidity providing means to allow
sample materials to be subjected to accelerated-irradiance exposure
factors for a significant period of time of about 3 to 10 days to
provide a corresponding time of about at least a years worth of
representative weathering of sample materials.
Description
[0001] This invention is a division of U.S. application Ser. No.
09/521,731 filed Mar. 9, 2000, which is a continuation-in-part of
U.S. application Ser. No. 09/006,746 filed Jan. 13, 1998.
BACKGROUND
[0003] 1. Field of the Invention
[0004] The invention relates to apparatus for subjecting materials
to accelerated irradiance exposure factors that permit about a
year's worth of representative weathering to be accumulated in a
period from about 3 to about 10 days, under controlled weathering
conditions that include several concurrent levels of temperature
and/or relative humidity at very high levels of natural
sunlight.
[0005] In the invention process, a solar concentrator [which may
include a High Flux Solar Furnace (HFSF) and an Irradiance
Redistribution Guide (IRG)] is used to obtain elevated levels
(25-100.times.) of concentrated sunlight for accelerated testing of
material samples. When an IRG is used, it provides the capability
of being able to modify (redistribute) the Gaussian-shaped beam
from the HFSF into a more uniform profile on a sample exposure
plane.
[0006] Also encompassed in the invention process for obtaining
ultra-accelerated natural sunlight exposure testing is the use of
reflective apparatus such as multi-step and multi-faceted
concentrators and refractive apparatus such as Fresnel lens
concentrators, holographic concentrators, 2D or 3D micro lens
arrays, and an array of Fresnel lens facets to obtain elevated
levels (25-100.times.) of concentrated sunlight for accelerated
natural sunlight testing of material samples.
[0007] By adequately controlling sample temperatures and
demonstrating that reciprocity relationships are obeyed (i.e., the
level of applied accelerated stresses does not change the
failure/degradation mechanism), this novel capability allows
materials to be subjected to accelerated irradiance exposure
factors of 25-100.times., thereby permitting a year's worth of
representative weathering (in terms of natural sunlight exposure)
to be accumulated in from about 3 to about 10 days.
[0008] 2. Description of the Prior Art
[0009] U.S. Pat. No. 4,817,447 discloses a weathering chamber using
lamps and sample temperature control using cooling air. Uniform
sample irradiance at accelerated levels of up to 10 suns (within
the UV bandwidth) appears attainable.
[0010] A test apparatus incorporating a mirror, which rejects
infrared, is disclosed in U.S. Pat. No. 4,012,954. In the '954
patent, convective cooling air and a conductively cooled substrate
are also incorporated. However, although convective cooling is
used, the air movement is not used to deliver humidity to the
samples during exposure; rather, humidity is provided by floating
the sample substrate in a water bath. Further, as in the case of
U.S. Pat. No. 4,817,477, the '954 patent uses artificial light
sources for exposure of the samples.
[0011] U.S. Pat. No. 3,686,940 discloses a water-cooled cylindrical
mirror, which rejects infrared radiation in an ultraviolet test
apparatus. In the '940 patent, natural sunlight is not used.
[0012] U.S. Pat. No. 4,627,287 disclose a light resistance tester
apparatus that eliminates nonuniformity of the temperature by
providing a flow divider in the lower region of a sample-holder
setting frame so that the circulating air can flow through the
central part of the tester around the xenon lamp without contacting
the surfaces of samples, thereby substantially eliminating the
nonuniformity of temperature due to such circulating air.
[0013] A solar weathering device with control of sample temperature
by cooling air is disclosed in U.S. Pat. No. 4,807,247. While this
patent uses natural sunlight, a sample irradiance at accelerated
levels of only up to 8 suns across the complete solar spectrum is
employed.
[0014] U.S. Pat. No. 5,138,892 discloses accelerated light fastness
testing of materials with xenon lamps and sample temperature
control using airflow. Sample irradiance at accelerated UV levels
of up to 8 suns (180 W/m.sup.2 between 300-400 nm) are attainable.
This patent does not utilize natural sunlight in its testing of
materials.
[0015] A weather test machine using xenon lamps and sample
temperature and humidity control using airflow is disclosed in U.S.
Pat. No. 5,646,358. Uniform sample irradiance at accelerated levels
up to 1-3 suns (within the UV bandwidth) is attainable. This patent
does not utilize natural sunlight in its weather test machine.
[0016] U.S. Pat. No. 5,153,780 discloses a dish reflector and
method for concentrating moderate solar flux uniformly on a target
plane, said dish having stepped reflective surface characterized by
a plurality of ring-like segments arranged about a common axis,
each segment having a concave spherical configuration.
[0017] 3. The Need for Capabilities Beyond the Prior Art
[0018] There is a need for devising facilities for
ultra-accelerated natural sunlight exposure testing of materials
and devices under controlled weathering conditions that include
several concurrent levels of temperature and/or relative humidity
at very high levels of natural sunlight. This need is associated
with the desirability to be able to predict the in-service
lifetimes of said materials and devices from correlation's derived
between such realistically accelerated test results and those
obtained during normal use conditions. Further, there is a need to
conduct these ultra-accelerated exposure tests at irradiance
exposure factors of from about 25 to 100 suns, wherein the
irradiance is highly uniform. The need to conduct these
ultra-accelerated natural sunlight exposure tests of materials and
devices should exclude artificial light sources which invariably
introduce uncertainties regarding realistic spectral content of the
irradiance stress on samples being exposed. For example, the use of
artificial light leads to unrealistic degradation mechanisms and
failure modes of exposed materials caused by low wavelength
(<300 nm) photons that are not present in terrestrial solar
spectra.
SUMMARY OF THE INVENTION
[0019] In light of the drawbacks of the foregoing prior art, a
general object of the present invention is to provide the unique
capability to carry out ultra-accelerated exposure testing of
materials and devices under controlled conditions that include
several concurrent levels of temperature and/or relative humidity
at very high levels of natural sunlight, thereby permitting about a
year's worth of representative weathering, in terms of natural
sunlight exposure, to be accumulated in from about 3 to about 10
days.
[0020] A further object of the present invention is to provide
ultra accelerated exposure testing of materials and devices by
controlling sample temperatures and humidities and demonstrating
that reciprocity relationships are obeyed (i.e., level of applied
accelerated stress does not change failure/degradation
mechanism).
[0021] A yet further object of the present invention is to provide
ultra-accelerated exposure testing of materials and devices that
allows materials to be subjected to accelerated irradiance exposure
factors of 25-100.times. to provide about a year's worth of
representative weathering, in terms of natural sunlight exposure,
to be accumulated in from about 3 to about 10 days.
[0022] A still further object of the invention is to provide a
method of carrying out ultra-accelerated exposure testing of
materials and devices utilizing a sample chamber that allows
control of temperature and humidity during light exposure; wherein
concentrated sunlight enters the chamber through an appropriate
window, which may include quartz.
[0023] A further object yet still of the invention is to provide a
method for carrying out ultra-accelerated exposure testing of
materials and devices utilizing a cold mirror as a filter that
reflects the ultraviolet/visible (UV/VIS) and transmits the near
infrared (NIR) part of the solar spectrum, since the short
wavelength (UV) light has been shown to be the predominant
deleterious stress experienced by materials and devices during
outdoor weathering.
[0024] Another object of the present invention is to provide a
method of carrying out ultra-accelerated exposure testing of
materials and devices under controlled weathering conditions,
wherein conductive cooling of sample materials is provided by a
water cooled substrate on to which samples are placed, and
convective cooling is provided by blowing moist or dry air over the
top surface of the samples, to provide high or low humidity to the
samples during exposure of redirected concentrated sunlight into
the exposure chamber to reduce the thermal load on the samples.
[0025] The invention is accomplished by the steps of: utilizing a
solar concentrator to obtain elevated levels (25-100.times.) of
concentrated sunlight with a uniform flux profile on the materials
or samples being tested; splitting the solar spectrum into
deleterious ultraviolet/visible (UV/VIS) light into the sample
chamber; transmitting concentrated near-infrared (NIR) radiation to
minimize undesirable thermal loading of material samples; and
further control of temperature and/or relative humidity experienced
by materials samples within the exposure chamber. The solar
spectrum is split at a cut-off wavelength .lambda..sub.cutoff such
that UV/VIS consists of wavelengths less than .lambda..sub.cutoff
and VIS/NIR consists of wavelengths greater than
.lambda..sub.cutoff. Various combinations of concentrator designs
(reflective and refractive), secondary reflectors, secondary
concentrators, and turning mirrors can be used to provide the
uniform flux. Additionally, the spectral splitting can be achieved
at various points in the system through the use of coatings applied
to any number of optical elements.
[0026] In terms of the best additional means for facilitating the
general effect of ultra-accelerated natural sunlight exposure
testing of materials, the facilities are as follows:
[0027] 1) Multi-faceted concentrator design with facets having the
following characteristics:
[0028] Hexagonal, circular, rectangular, and triangular shaped
facets arranged in a close packed array;
[0029] Facet centers located on a plane, parabola, sphere or other
non-analytic shape;
[0030] Facet curvature that is flat, spherical, parabolic or
aspheric; and
[0031] Facet reflector coatings designed to reflect UV light and
transmit visible and IR, in the following configurations:
[0032] a) Multi-faceted concentrator with geometry and design of
facets to produce uniform flux on a sample chamber located at or
near the aim point of the facets
[0033] b) Multi-faceted concentrator with secondary reflector
designed to deliver uniform flux to the sample chamber located near
the center of the facet array
[0034] c) Multi-faceted concentrator with secondary concentrator
designed to deliver uniform flux to the sample chamber located near
the exit of the secondary
[0035] d) Multi-faceted concentrator with secondary reflector
designed to deliver uniform flux to the sample chamber located
below the secondary to allow a horizontal orientation of the sample
chamber.
[0036] e) Multi-faceted concentrator with secondary reflector
designed to deliver uniform flux to the sample chamber located
below a turning mirror placed near the center of the facet
array.
[0037] f) Multi-faceted concentrator with secondary reflector
designed to deliver uniform flux to the sample chamber below a
turning mirror placed near the center of the facet array.
[0038] 2) The multi-step concentrator of U.S. Pat. No. 5,153,780
"Method and Apparatus for Uniformly Concentrating Solar Flux for PV
Applications using a reflector coating designed to reflect UV light
and transmit VIS and NIR in the following configurations:
[0039] a) Multi-step concentrator with geometry and design of steps
to produce uniform flux on a sample chamber located at or near the
aim point of the various steps
[0040] b) Multi-step concentrator with secondary reflector designed
to deliver uniform flux to the sample chamber located near the
center of the multi-step concentrator
[0041] c) Multi-step concentrator with secondary concentrator
designed to deliver uniform flux to the sample chamber located near
the exit of the secondary
[0042] d) Multi-step concentrator with secondary reflector designed
to deliver uniform flux to the sample chamber located below the
secondary to allow a horizontal orientation of the sample
chamber,
[0043] e) Multi-step concentrator with secondary reflector designed
to deliver uniform flux to the sample chamber located below a
turning mirror placed near the center of the multi-step
concentrator
[0044] f) Multi-step concentrator with secondary reflector designed
to deliver uniform flux to the sample chamber below a turning
mirror placed near the center of the multi-step concentrator
[0045] 3) Fresnel lens concentrator/heat mirror configurations that
only permit the desired spectral range to be transmitted:
[0046] a) with heat mirror positioned above the top surface of the
lens
[0047] b) with one or both surfaces of the lens having a heat
mirror coating
[0048] c) with heat mirror positioned between the lens and the
sample
[0049] d) with heat mirror positioned between the lens and sample,
but oriented as a relay mirror to reflect the desired wavelengths
to a position perpendicular to the plane of the lens
[0050] e) a two-stage Fresnel lens that interact as paired prisms
to provide spectral selectivity
[0051] f) any of the above configurations combined with a secondary
concentrator to achieve the desired flux uniformity
[0052] 4) Holographic concentrator in the following
configurations:
[0053] a) achieves both spectral splitting and uniform
concentration in its fundamental design
[0054] b) provides spectral splitting in its fundamental design and
uses a secondary concentrator to achieve the uniform flux
[0055] c) concentrates in its fundamental design and uses a
secondary concentrator to achieve the uniform flux, but with a cold
mirror coating on the secondary
[0056] d) provides uniform flux in its fundamental design and uses
a cold mirror to achieve the spectral splitting
[0057] e) concentrates in its fundamental design and uses a
secondary concentrator to achieve the uniform flux, but with a cold
mirror placed between the lens and secondary to achieve the
spectral splitting
[0058] 5) Use of a 2D or 3D micro lens array to achieve flux
uniformity and/or spectral splitting
[0059] 6) An array of Fresnel lens facets can be used to achieve
flux uniformity and in conjunction with a heat mirror or a cold
mirror can provide spectral splitting
BRIEF DESCRIPTION OF THE DRAWINGS
[0060] The drawings that are incorporated in and form part of the
specification will illustrate alternative embodiments of the
invention, and serve together with the description to explain the
principles of the invention wherein:
[0061] FIG. 1 shows a multi-faceted concentrator design that
receives incident natural sunlight. The design transmits VIS/NIR
and reflects UV/VIS onto a sample exposure plane.
[0062] FIG. 2 shows a multi-faceted design that transmits VIS/NIR
and reflects UV/VIS onto a secondary reflector, which in turn
reflects uniformly concentrated natural sunlight onto a sample
exposure plane.
[0063] FIG. 3 shows a multi-faceted concentrator design for
affecting ultra-accelerated natural sunlight exposure testing, in
which natural sunlight is made incident upon a multi-faceted design
that transmits VIS/NIR and reflects UV/VIS through a secondary
concentrator and onto a sample exposure plane.
[0064] FIG. 4 shows a multi-faceted concentrator design with a
secondary reflector that delivers uniform flux to a sample chamber
located below the secondary reflector to allow a horizontal
orientation of the sample chamber.
[0065] FIG. 5 shows a multi-faceted concentrator with a secondary
reflector designed to deliver uniform flux to a sample exposure
plane in a chamber located below a turning mirror.
[0066] FIG. 6 shows a multi-faceted concentrator design that
contains a reflector coating to reflect the full solar spectrum
onto a secondary reflector that transmits VIS/NIR and reflects
UV/VIS onto a sample exposure plane.
[0067] FIG. 7 shows a multi-faceted concentrator design that
reflects the full solar spectrum onto a secondary reflector that in
turn reflects only UV/VIS onto a horizontally disposed sample
exposure plane.
[0068] FIG. 8 shows a multi-faceted concentrator design that
reflects the full solar spectrum UV/VIS/NIR. The full solar
spectrum is reflected onto a secondary reflector that transmits
VIS/NIR and reflects UV/VIS onto a turning mirror that reflects the
UV/VIS onto a horizontally disposed sample exposure plane.
[0069] FIG. 9 shows a multi-stepped concentrator design for
uniformly concentrating solar flux, in which a plural-stepped
concentrator having reflective surfaces is used to reflect UV/VIS
onto a sample exposure plane and transmit VIS/NIR. Other
combinations of elements can be used with the multi-stepped
concentrator including a secondary reflector or turning mirror to
allow repositioning of the sample exposure chamber.
[0070] FIG. 10 shows a heat mirror positioned above the top surface
of a Fresnel lens to allow only the desired spectral range to be
transmitted and the Fresnel lens is used to uniformly concentrate
the UV/VIS.
[0071] FIG. 11 shows another use of the Fresnel lens in which one
or both surfaces of the Fresnel lens has a heat mirror coating that
allows only the desired spectral range to be transmitted and the
Fresnel lens is used to uniformly concentrates the UV/VIS.
[0072] FIG. 12 shows a Fresnel lens in which a heat mirror is
positioned between the Fresnel lens and the sample plane to allow
only the spectral range to be transmitted and the Fresnel lens is
used to uniformly concentrate the UV/VIS.
[0073] FIG. 13 shows a Fresnel lens that provides uniform
concentrated light on a sample exposure plane that is perpendicular
to the plane of the Fresnel lens and uses a relay minor that
performs the desired spectral splitting and is positioned at an
appropriate angle to achieve uniformity.
[0074] FIG. 14 shows a two-stage (double-layer) Fresnel lens
arrangement in which the surface geometry is such that the desired
concentrated uniformity over the required area in the sample
exposure plane is achieved but the surface features of the two
arrays (separated by low-index of refraction media such as air with
n=1) interact as paired prism elements to provide spectral
selectivity.
[0075] FIG. 15 shows a refractive means by which the spatial
splitting of wavelengths can be accomplished by using a pair of
dispersion prisms to achieve spectral selectivity.
[0076] FIG. 16 takes any of the configurations described in FIGS.
10 to 14 above in which a secondary concentrator is incorporated to
achieve the desired flux uniformity and/or to reposition the sample
exposure plane to a more desirable orientation (i.e., horizontal)
during exposure testing (where the secondary concentrator may also
be used to perform spectral selectivity, as for example,
functioning also as a cold mirror).
[0077] FIG. 17 shows a holographic device that concentrates the
solar irradiance and performs the desired spectral splitting and
provides flux uniformity over the required area in a sample
exposure plane.
[0078] FIG. 18 shows a holographic device that concentrates the
solar irradiance and performs the desired spectral splitting and
uses a secondary concentrator to provide flux uniformity over the
required area in a sample exposure plane (SEP).
[0079] FIG. 19 shows a holographic device that concentrates the
solar irradiance and provides flux uniformity over the required
area in a sample exposure plane, and uses a cold mirror to achieve
the desired spectral splitting.
[0080] FIG. 20 shows a holographic device that concentrates the
solar irradiance and provides flux uniformity over the required
area in a sample exposure plane, and uses a heat mirror to achieve
the desired spectral splitting.
[0081] FIG. 21 shows a holographic device that concentrates the
solar irradiance and uses a secondary concentrator to provide flux
uniformity over the required area in a sample exposure plane and
also uses the secondary concentrator to achieve the desired
spectral splitting.
[0082] FIG. 22 shows a holographic device that concentrates the
solar irradiance and uses a secondary concentrator to provide flux
uniformity over the required area in a sample exposure plane and
uses a heat mirror to achieve the desired spectral splitting.
[0083] FIG. 23 utilizes any of the configurations described in
FIGS. 17-22 above, in which a secondary concentrator is
incorporated to achieve the desired flux uniformity and/or to
reposition the sample exposure plane to a more desirable
orientation (e.g., horizontal) during exposure testing.
[0084] FIG. 24 shows as a means for refractively achieving
concentrated solar irradiance and/or spectral splitting and/or flux
uniformity with a 2-dimensional or 3-dimensional array of
microlenses.
[0085] FIG. 25 shows a multi-faceted refractive element MFRE (i.e.,
lenses or Fresnel lenses) used in conjunction with a heat
mirror.
[0086] FIG. 26 shows a cut-away view of an advanced exposure
chamber design in accordance with the invention.
[0087] FIGS. 27a, 27b and 27c show additional views of the
embodiment of the exposure chamber design of FIG. 26.
[0088] FIG. 28 is a perspective view of the system layout of the
apparatus of the invention showing the sample chamber interface,
via a cold mirror, with the HFSF/IRG components.
[0089] FIG. 29 shows the sample exposure chamber detail design that
allows two levels of temperature and two levels of relative
humidity to be maintained during sunlight exposure for the
apparatus of the invention and ability to monitor spatial and
spectral uniformity of the solar beam in situ during sample
exposure; wherein:
[0090] FIG. 29a shows a top view of the heating/cooling chamber
with samples in place.
[0091] FIG. 29b shows a top view of the chamber with humidity
chamber in place.
[0092] FIG. 29c is a side view of the heating/cooling chamber.
[0093] FIG. 29d is a side view of the humidity chamber.
Preferred Means for Facilitating Ultra-Accelerated Natural Sunlight
Exposure Testing
[0094] Referring flow to FIG. 1, there is shown a multi-faceted
concentrator design MF that receives incident natural sunlight NS.
The multi-faceted design transmits VIS/NIR and reflects UV/VIS onto
a sample exposure plane SEP in chamber means (not shown) that
provide single or multiple concurrent levels of temperature and/or
relative humidity to facilitate accelerated aging.
[0095] Natural sunlight NS is made incident on yet another
multi-faceted MF design as shown in FIG. 2. In this figure, the
multi-faceted design transmits VIS/NIR and reflects UV/VIS onto a
secondary reflector SR, which in turn reflects uniformly
concentrated natural sunlight onto the sample exposure plane SEP
located in chamber means that provide single or multiple concurrent
levels of temperature and/or relative humidity to facilitate
weathering of sample materials.
[0096] A multi-faceted concentrator design for affecting
ultra-accelerated natural sunlight exposure testing is shown in
FIG. 3 in which natural sunlight NS is made incident upon a
multi-faceted design that transmits VIS/NIR and reflects UV/VIS
through a secondary concentrator SC and onto a sample exposure
plane SEP disposed within chamber means that provide single or
multiple concurrent levels of temperature and/or relative
humidity.
[0097] A multi-faceted concentrator MF design configuration with a
secondary reflector SR designed to deliver uniform flux to a sample
chamber located below the secondary reflector to allow a horizontal
orientation of the sample chamber is shown in FIG. 4, in which
natural sunlight NS is made incident upon the multi-faceted
concentrator that transmits VIS/NIR and reflects UV/VIS onto the
secondary reflector SR, which in turn, reflects a uniform flux of
UV/VIS onto the horizontally disposed sample exposure plane SEP
within chamber means that provide single or multiple concurrent
levels of temperature and/or relative humidity.
[0098] A multi-faceted concentrator MF with a secondary reflector
SR designed to deliver uniform flux to a sample exposure plane SEP
in a chamber located below a turning mirror TM is shown in FIG. 5.
In this figure, natural sunlight NS is made incident upon MF which
transmits VIS/NIR and reflects UV/VIS onto secondary reflector SR
which reflects a uniform flux onto a turning mirror TM, that in
turn reflects UV/VIS onto a sample exposure plane SEP in chamber
means that provide single or multiple concurrent levels of
temperature and/or relative humidity to cause accelerated
weathering.
[0099] A multi-faceted concentrator MF that contains a reflector
coating to reflect the full solar spectrum is shown in FIG. 6. In
FIG. 6 natural sunlight is made incident upon the multi-faceted
reflector coating, and the full spectrum UV/VIS/NIR is reflected
onto a secondary reflector SR, which transmits VIS/NIR and reflects
UV/VIS onto a sample exposure plane SEP located in chamber means
that provide single or multiple concurrent levels of temperature
and/or relative humidity to facilitate accelerated aging of the
test sample.
[0100] A multi-faceted concentrator design MF that reflects the
full solar spectrum onto a secondary reflector SR that in turn
reflects only UV/VIS onto a horizontally disposed sample exposure
plane SEP is shown in FIG. 7.
[0101] FIG. 8 shows a multi-faceted concentrator design MF that
also reflects the full solar spectrum UV/VIS/NIR. The UV/VIS/NIR is
reflected onto a secondary reflector SR which transmits VIS/NIR and
reflects UV/VIS onto a turning mirror TM that reflects the UV/VIS
onto a horizontally disposed sample exposure plane SEP located in
chamber means that provide concurrent levels of temperature and/or
relative humidity to facilitate accelerated aging of the sample
material.
[0102] In FIG. 9, a multi-stepped concentrator design for uniformly
concentrating solar flux is shown, in which a plural-stepped
concentrator dish 10 having reflective surfaces comprised of for
example, 5 reflective surface elements, including a hub element
designated by n1 and ring-shaped reflective elements n2-n5, lies
symmetrically about a common axis A. The reflective elements n1-n5
are definable by reference dish RD, an imaginary parabolic dish
that shares a common axis A, as shown. Reference dish RD has a
focal length F and a target plane TP perpendicular to the A axis,
at a distance equal to the focal length F from the vertex V, and
the sample exposure plane SEP located in chamber means that provide
single or multiple concurrent levels of temperature and/or relative
humidity to facilitate accelerated aging. The multi-step
concentrator employs a reflector coating RC that reflects UV/VIS
onto the SEP and transmits VIS/NIR.
[0103] Alternative design configurations to the multi-step
concentrator with geometry and design of facets to produce uniform
flux on a sample chamber located at or near the aim point of the
facets (as shown in FIG. 9), can be: a multi-step concentrator with
secondary reflector designed to deliver uniform flux to the sample
chamber located near the center of the facet array; a multi-step
concentrator with secondary concentrator designed to deliver
uniform flux to the sample chamber located near the exit of the
secondary concentrator; a multi-step concentrator with secondary
reflector designed to deliver uniform flux to the sample chamber
located below the secondary concentrator to allow a horizontal
orientation of the sample chamber; and a multi-step concentrator
with secondary reflector designed to deliver uniform flux to the
sample chamber below a turning mirror placed near the center near
the facet array.
[0104] Referring now to FIG. 10, it can be seen that uniform,
non-concentrated natural sunlight NS is incident on a heat mirror
HM which reflects VIS/NIR but transmits UV/VIS. The UV/VIS is
transmitted to a Fresnel lens FL to permit only the desired
spectral range of uniform concentrated spectrally split natural
sunlight D to be incident upon the sample exposure plane SEP.
[0105] One or both of the surfaces of a Fresnel lens may be
provided with a heat mirror coating HMC that allows the desired
spectral range to be transmitted, as is shown in FIG. 11, where
uniform, non-concentrated incident natural sunlight NS is made
incident upon a heat mirror coating HMC on either the top or bottom
or both sides of a Fresnel lens FL, so that UV/VIS is transmitted
onto a sample exposure plane SEP.
[0106] Another of the preferred embodiments for facilitating
ultra-accelerated natural sunlight exposure testing is by a heat
mirror HM positioned between a Fresnel lens and the sample plane to
permit only the desired spectral range to be transmitted, as is
shown in FIG. 12. In FIG. 12, uniform, non-concentrated incident
natural sunlight NS is made incident to a Fresnel lens FL which
transmits a uniformly-concentrated, broad-band spectral range to a
heat mirror HM that reflects VIS/NIR, but transmits UV/VIS onto a
sample exposure plane SEP.
[0107] In a further preferred embodiment, as shown in FIG. 13, a
Fresnel lens FL is designed to provide uniform non-concentrated
incident sunlight NS and transmits the full spectral range onto a
cold relay mirror, which in turn transmits VIS/NIR and reflects
UV/VIS onto a sample exposure plane SEP.
[0108] In the preferred embodiment of FIG. 14, a 2-stage or double
layer uniform concentrated UV/VIS Fresnel lens arrangement is used
in which the surface geometry is such that not only is the desired
concentrated uniformity over the required area in the sample
exposure plane achieved but the surface features of the arrays
(separated by a low-index of refraction media, such as air with
n=1) interacts as paired prism elements to provide spectral
selectivity. In FIG. 14, uniform non-concentrated natural sunlight
NS is made incident to a first Fresnel/prism array FLA 1 so that
the light is spatially separated into distinct wavelengths
("rainbow"). A masking pattern is then placed on to the top surface
of a second Fresnel prism array FLA 2 to block unwanted
wavelengths>.lambda..sub.cutoff (i.e. high VIS and NIR) such
that the light exiting FLA 2 is recombined light with a
.lambda.<.lambda..sub.c- utoff prior to directing the
re-combined light with the .lambda.<.lambda..sub.cutoff onto a
sample exposure plane SEP.
[0109] A pair of dispersion prisms (1 and 2) can be used to achieve
spectral selectivity in the following manner, as shown by FIG. 15,
in which there is-first made an input of uniform distribution of
the full solar spectrum FSS through a first prism to affect
spatially separated/distinct wavelengths SSDW on the one hand and
to cause adjustable stop blocks of transmitted wavelengths
accelerated .lambda.>.lambda..sub.UV/VIS or
.lambda.>.lambda..sub.cutoff, and in which prism No. 2 is used
to re-construct or homogenize the spatially selected wavelengths
from prism No. 1 to obtain an output uniform distribution of
spectrally selected light UDSSL with
.lambda.<.lambda..sub.cutoff, which is then concentrated in a
Fresnel lens-like manner. In this connection, it should be noted
that the adjustable stop blocks can be directly applied to the
first surface of prism No. 2 (as for example by the use of black
paint).
[0110] In general, any of the configurations described in FIGS.
10-14, in which a secondary concentrator is incorporated to achieve
the desired flux uniformity and/or to reposition the sample
exposure plane to a more desirable orientation (i.e., horizontal)
during exposure testing may be suitable and it should be noted that
the secondary concentrator may also be used to perform the spectral
selectivity, for example, so as to be able to function as a cold
mirror as is shown in FIG. 16. In FIG. 16, uniform,
non-concentrated natural sunlight NS is made incident upon a
tracking primary Fresnel lens array FLA, and from which the
transmissions are adjusted with a secondary concentrator SC that
adjusts with primary tracking. The secondary concentrator transmits
VIS/NIR (as is done with a cold mirror) where upon uniform
concentrated UV/VIS is then reflected onto a fixed horizontal
sample exposure plane SEP.
[0111] The specific embodiment of FIG. 17 shows a holographic
device that concentrates the solar irradiance and performs the
desired spectral splitting and provides flux uniformity over the
required area in a sample exposure plane. More specifically, in
FIG. 17, uniform, non-concentrated natural sunlight NS is made
incident upon a holographic device HD which directs concentrated
UV/VIS onto a sample exposure plane SEP, and the spectrally split
VIS/NIR is made to miss the sample exposure plane.
[0112] In the preferred embodiment of FIG. 18, there is shown a
holographic device that concentrates the solar irradiance and
performs the desired spectral splitting and uses a secondary
concentrator to provide flux uniformity over the required area in
the sample exposure plane. More specifically, in FIG. 18, uniform
non-concentrated natural sunlight NS is made incident upon a
holographic device HD, which spectrally splits the incident light
into a non-uniform concentrated UV/VIS input so that it falls on a
secondary concentrator SC to provide a uniform concentrated UV/VIS
output on the sample exposure plane SEP, and whereby the
non-uniform concentrated VIS/NIR is split away from the secondary
concentrator.
[0113] In yet another preferred embodiment, as shown in FIG. 19, a
holographic device HD is used to direct uniform, non-concentrated
natural sunlight NS, where upon the incident NS is directed through
the HD to transmit VIS/NIR onto a cold mirror CM that reflects
UV/VIS onto a sample exposure plane SEP.
[0114] A still further embodiment of the invention as is shown in
FIG. 20, which utilizes a holographic device that concentrates the
solar irradiance and provides flux uniformity over the required
area in a sample exposure plane and utilizes a heat mirror to
achieve the desired spectral splitting (UV+low-VIS versus
high-VIS+NIR). In particular, the holographic device HD is utilized
to direct uniform, non-concentrated natural sunlight NS through a
heat minor HM to effect spectral splitting so that, UV/VIS is
transmitted onto a sample exposure plane SEP and the VIS/NIR is
reflected off of the heat mirror.
[0115] A holographic device HD through which uniform,
non-concentrated natural sunlight NS is directed is shown in FIG.
21. In the preferred embodiment of FIG. 21, the holographic device
directs the incident NS so that transmitted VIS/NIR is passed
through a secondary concentrator cold mirror SCCM and UV/VIS is
reflected from the SCCM onto a sample exposure plane SEP.
[0116] In the specific embodiment shown in FIG. 22, a holographic
device HD is utilized to direct uniform, non-concentrated natural
sunlight NS onto a heat mirror HM that transmits concentrated
non-uniform UV/VIS flux onto a secondary concentrator SC, which
concentrates uniform UV/VIS flux onto a sample exposure plane SEP,
while the heat mirror simultaneously reflects VIS/NIR.
[0117] Any of the facilities shown in the configurations of FIGS.
17-22, in which a secondary concentrator SC is incorporated to
achieve the desired flux uniformity and/or reposition the sample
exposure plane to a more desirable orientation (for example,
horizontal) during operation can be used by adjusting the secondary
concentrator with primary tracking, as is shown in the specific
embodiment of FIG. 23. In FIG. 23, uniform non-concentrated natural
sunlight NS is directed through a holographic device HD so that the
UV/VIS portion of the NS is reflected off of a secondary
concentrator SC (and the VIS/NIR portion is transmitted) that is
adjusted with primary tracking so as to reflect uniformly
concentrated natural sunlight onto a horizontal fixed sample plane
HFSP. VIS/NIR is transmitted by the SC.
[0118] Another means for refractively achieving concentrated solar
irradiance and/or spectral splitting and/or flux uniformity is with
a 2-dimensional or 3-dimensional array of micro lenses. In this
connection, reference is made to FIG. 24 in which such an array of
micro lenses is shown in cross section. As can be seen in FIG. 24,
a cross sections view of the 2-dimensional or 3-dimensional array
of micro lenses in which the individual lenses IL is shown. A top
view of the individual micro lenses is also shown.
[0119] Just as multi-faceted reflective elements can be used to
achieve uniform concentration, multifaceted refractive elements
(i.e., lenses or Fresnel lenses) can be used in conjunction with
heat mirrors and/or cold mirrors and/or secondary concentrators, as
is shown in FIG. 25. In FIG. 25, uniform, non-concentrated natural
sunlight NS is directed through a multi-faceted array of lenses
MFRE onto a heat mirror HM which transmits UV/VIS onto a sample
exposure plane SEP and reflects VIS/NIR. This multi-faceted array
of lenses may also be substituted for holographic devices shown in
the embodiments of FIGS. 17-23, where heat and/or cold mirror
coatings are applied to the lenses or separate elements or are
incorporated into secondary concentrators.
[0120] FIG. 26 is a top view of an alternative embodiment of the
exposure chamber design, showing a cut-away view. Samples 90 are
disposed so that they are separated by a chamber divider 91. The
chamber divider is in turn separated by an insulation divider 92.
In this embodiment, larger heating/cooling ports 93 are disposed
below the humidity ports 94.
[0121] As can be seen from the embodiment in FIG. 27, a number of
alternative ways exist for improving the performance and ease of
use of the sample exposure chamber. For example, baffles may be
added with heating and cooling using a circulating bath with an
approximate range of -20 to 100.degree. C., thereby eliminating the
need for individual electric cartridge heaters that give rise to
non-uniform sample exposure temperatures within a given quadrant.
The baffles and chambers may be machined out of one solid block of
aluminum and enlarged slightly. This would allow more room for
thermocouple wires and insulation and also provide a better seal
between chambers. In addition, an insulated, outside shell may be
fabricated, that both chambers would rest in. This design
configuration helps keep temperatures constant and makes the
assembly solid.
[0122] FIG. 27 is a top view of FIG. 26 minus the samples. FIG. 27b
is a view taken along the line A-A of FIG. 27a, showing the quartz
cover plate 100, humidity chamber 101, the insulation 102, a
heating/cooling chamber with baffles 103, fiber optic guides 104,
and an insulated box 105, around the chambers.
[0123] FIG. 28 shows the cross-sectional system layout of the IRG
106, cold mirror 107 and sample chamber 108, wherein incident
concentrated sunlight ICS is passed through the IRG and uniform
sunlight US exits. An improved chamber was designed and fabricated
that allows up to four replicate samples of about 2.2 cm.times.2.2
cm square in size each to be exposed to the same high level of
accelerated solar flux at two levels each of temperature and
[0124] humidity. For example, at a given flux (e.g., 50.times.
suns), sets of samples can be simultaneously exposed at Tlow,
RHlow, Tlow, Rlhigh; Thigh, RHlow; and Thigh, RH high. This allows
a fourfold increase in experimental throughput at a particular
exposure flux.
[0125] A detailed drawing of the sample exposure chamber is shown
in FIG. 29. FIG. 29a is a top view of the heating/cooling chamber
with samples S in place, and showing heating/cooling parts HCP.
FIG. 29b is a top view of the chamber with the humidity chamber in
place. During testing the samples are mechanically attached to the
top surface of the heating/cooling chamber to provide good thermal
contact. The humidity chamber sits atop the heating/cooling
chamber. FIG. 29c is a side view of the heating/cooling chamber,
showing the pathway P for fiber optic probes and the cross section
view of the heaters 109. FIG. 29d is a side view of the humidity
chamber showing the humidity ports HP and the highly transmissive
quartz window 110.
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